Chemistry of dichloromethane destruction in atmospheric-pressure gas streams by a dielectric packed-bed plasma reactor

C. Fitzsimmons, F. Ismail, J. C. Whitehead, J. J. Wilman

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The destruction of dichloromethane by a nonthermal plasma in atmospheric-pressure gas streams of nitrogen with variable amounts of added oxygen has been investigated. The identities and concentrations of the end products are determined by on-line FTIR spectroscopy, and the plasma chemistry is interpreted using a kinetic modeling scheme. Peak destructions of 20% are found for a deposited energy of 66 J L-1. The maximum dissociation is found for a carrier gas that contains 1-3% O2, and the dissociation is greater in pure nitrogen than in an air stream. The major end products of the processing are HCN, Cl2, and HCl in pure nitrogen and CO, COCl2, HCl, and Cl2 for gas streams containing oxygen. The plasma processing in streams containing oxygen also produces significant yields of nitrogen oxides. The mechanism of dichloromethane destruction in the plasma is predominantly oxidation initiated by atomic chlorine that is produced by collisions of dichloromethane with electronically excited nitrogen atoms and molecules. Because of low cross sections, electron attachment does not play a role in the destruction of dichloromethane. The addition of oxygen to the gas streams initially causes additional destruction from O and OH reactions, but further increase in the oxygen concentration causes inhibition of both the atomic chlorine cycle and the formation of NOx and a consequent reduction in dichloromethane destruction.
    Original languageEnglish
    Pages (from-to)6032-6038
    Number of pages6
    JournalJournal of Physical Chemistry A
    Volume104
    Issue number25
    DOIs
    Publication statusPublished - 29 Jun 2000

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